Gastrointestinal - Hepatitis Midterm Notes PDF

5 1 GASTROINTESTINAL – Hepa%%s Hepa%%s Overview Hepa''s is defined as inflamma%on of the liver, which can be acute or chronic. Hepa''s can result from a variety of causes, most notably viral infec'ons (...

5 1 GASTROINTESTINAL – Hepa%%s Hepa%%s Overview Hepa''s is defined as inflamma%on of the liver, which can be acute or chronic. Hepa''s can result from a variety of causes, most notably viral infec'ons (Hepa''s A, B, C, D, and E), as well as alcohol abuse, toxins, autoimmune disorders, and certain medica'ons. 1. Most Likely Cause The most likely causes of hepa''s vary depending on the type. The main causes include: Viral Hepa%%s: o Hepa%%s A: Caused by Hepa%%s A virus (HAV). o Hepa%%s B: Caused by Hepa%%s B virus (HBV). o Hepa%%s C: Caused by Hepa%%s C virus (HCV). o Hepa%%s D: Caused by Hepa%%s D virus (HDV), but it can only infect a person who is already infected with Hepa%%s B. o Hepa%%s E: Caused by Hepa%%s E virus (HEV). Non-viral Hepa%%s: o Alcohol-induced hepa%%s: Caused by the toxic effects of acetaldehyde, a metabolite of alcohol. o Drug-induced hepa%%s: Triggered by hepatotoxic medica'ons, such as acetaminophen, NSAIDs, and certain an'bio'cs. o Autoimmune hepa%%s: Caused by the immune system aIacking hepatocytes (liver cells), oJen linked to the presence of an%nuclear an%bodies (ANA) and an%-smooth muscle an%bodies (ASMA). o Non-alcoholic steatohepa%%s (NASH): Caused by the accumula'on of fat in hepatocytes due to metabolic dysfunc'on, commonly seen in obesity, diabetes, and metabolic syndrome. 2. Pathophysiology The pathophysiology of hepa''s depends on the specific cause but generally follows these steps: 1. Infec%on/Exposure: o In viral hepa%%s, the virus infects hepatocytes in the liver, where it replicates and triggers an immune response. o In alcoholic hepa%%s, acetaldehyde disrupts normal hepatocyte func'on and promotes oxida%ve stress, leading to cellular injury and inflamma'on. o In autoimmune hepa%%s, T cells aRack hepatocytes, triggering an immune response that leads to hepatocyte destruc'on. 2. Inflammatory Response: o The immune system targets infected hepatocytes or those damaged by toxins, resul'ng in the recruitment of macrophages, cytokines, and natural killer (NK) cells.  2 o This process leads to hepatocyte necrosis, release of liver enzymes (AST, ALT) into the bloodstream, and the produc'on of fibrosis (scar %ssue) over 'me. 3. Liver Damage and Scarring: o Persistent inflamma'on promotes fibrosis, which impairs hepa'c blood flow and bile excre'on. o If unresolved, fibrosis progresses to cirrhosis (F4 fibrosis stage), where the liver's architecture is permanently altered, leading to portal hypertension and liver dysfunc'on. o If cirrhosis progresses, it increases the risk of hepatocellular carcinoma (HCC). 4. Chronic Hepa%%s: o Chronic hepa''s (e.g., Hepa%%s B, C, D) may persist due to the inability of the immune system to completely eliminate the virus. o Chronic infec'on results in ongoing inflamma'on, which promotes fibrosis and the risk of cirrhosis and liver cancer. 3. Disease Transmission The mode of transmission depends on the specific cause of hepa''s. Hepa%%s A: TransmiIed via the fecal-oral route, oJen through contaminated food, water, or close contact with infected individuals. Hepa%%s B: TransmiIed through contact with infected blood, bodily fluids (semen, vaginal fluid), sexual contact, and ver%cal transmission (mother-to-infant). Hepa%%s C: TransmiIed through infected blood, oJen through needle-sharing, blood transfusions, and contaminated medical equipment. Hepa%%s D: Can only infect individuals who are already infected with Hepa%%s B. TransmiIed in the same way as HBV (blood, sexual contact, ver'cal transmission). Hepa%%s E: TransmiIed via the fecal-oral route, similar to Hepa''s A, but it is more dangerous in pregnant women. Non-viral Hepa%%s: These types of hepa''s are not infec'ous. They occur due to toxin exposure, alcohol consump%on, and autoimmune processes, and they cannot be transmiIed from person to person. 4. Risk Factors The risk factors for hepa''s vary by type. Viral Hepa%%s Hepa%%s A: o Travel to endemic areas with poor sanita'on. o Inges%on of contaminated food or water. o Close contact with infected individuals. Hepa%%s B: o Unprotected sex with mul%ple partners. o Sharing needles, syringes, or drug equipment. o Healthcare exposure (e.g., needles'ck injuries). o Ver%cal transmission from mother to child during childbirth. Hepa%%s C:  3 o Injec%on drug use (shared needles). o Blood transfusions before 1992 (before screening procedures). o Needles%ck injuries among healthcare workers. Hepa%%s D: o Risk factors are the same as Hepa%%s B, since HDV only co-infects with HBV. Hepa%%s E: o Travel to endemic areas (like Southeast Asia). o Contaminated water (similar to Hepa''s A). o Pregnancy increases the risk of severe illness from Hepa''s E. Non-viral Hepa%%s Alcoholic Hepa%%s: o Chronic alcohol consump%on (long-term heavy drinking). Drug-induced Hepa%%s: o Use of hepatotoxic drugs (e.g., acetaminophen, NSAIDs, sulfa an%bio%cs). Autoimmune Hepa%%s: o Presence of autoimmune diseases like rheumatoid arthri%s. Non-alcoholic Steatohepa%%s (NASH): o Obesity, Type 2 diabetes, and Metabolic syndrome. o Poor diet (high fat, high sugar). Summary Table Criteria Hepa%%s Most Likely Viruses (A, B, C, D, E), alcohol, toxins, autoimmune diseases【. Cause Involves viral infec'on, immune aIack on hepatocytes, oxida've stress Pathophysiology (alcohol), and fibrosis. Depends on type (e.g., fecal-oral for HAV, HEV; bloodborne for HBV, HCV, Transmission HDV). Drug use, unprotected sex, poor sanita'on, healthcare exposure, obesity, Risk Factors diabetes, alcohol use.